updated README and CHANGELOG

-updated README and CHANGELOG

Update cnc_build.h

Merge pull request #64 from Paciente8159/v1.2.1

v1.2.1

Merge branch 'v1.2'

Merge pull request #40 from Paciente8159/stm32-pinconfig-fix

stm32 pin configuration fix

Merge pull request #34 from Paciente8159/debouncing

Added limit switch software debouncing option to µCNC (on AVR is built around RTC functions)

Update parser.c

- fix settings change bug

Update parser.c

- fix parser reset states to match RS274 standard

Merge pull request #10 from Paciente8159/1.0.0-rc

1.0.0-rc

Merge pull request #9 from Paciente8159/1.0.0-beta.2

1.0.0 beta.2